Posted my problem a few weeks ago but got not replys so I paid a guy to use his diagonostic computer on my merc to see what it came up with. The fault shown was 'rear axle speed sensor'. Before I go buy the part and try to fit it I thought I'd bounce this solution off you guys to see if you thought it was a plausable solution to the problem. The difficulity I have is that the problem does some how seem to be temperature related as the fault clears at normal temps - as explained below. I did charge the battety without removing the batery supply to the car as the car was off road for a few months so maybe I have blown some electronic component????????

Problem is:
My 1997 C180 was off road for 2 months and when I put it back on road it had a problem. When I start it the ABS light stays on and when I select drive it jerks hard into gear - not the smooth gear select I got previously. The car drives but only in the 1 gear and the ABS light stays on. If I drive in 1 gear until the engine is up to normal temp (and not before) and then stop the car, turn the engine off and restart the ABS light is still on but when I select drive it selects gear smoothly and drives away, the ABS light goes out after a few seconds and the gears change normally. I can stop and start or drive for ever and all remain OK if the temp is at normal. If I stop and let the car stand and go below normal temp then the problem comes back but always goes away if turned off and on after reaching normal temp.

 

A few things spring to mind. Not sure if they will be any help but here goes...

Did your battery run flat while the car was parked up ? Did you have to use a battery charger or jump/booster cables to get it started ?

If so then there may be some corruption in the ECU. Disconnecting the battery for a while and reconnecting it may cure the problem.

The ECU is responsible for switching on the ABS light and also for operating the vacuum inhibit valve which prevents the car from changing gear until the engine reaches running temperature. Obviously yours is being extremely over-zelous but it's a thought. Normally your car will be a little longer changing from second to third if you park for a short time when the engine is hot and then start off again. This is intentional. It's so that the catalytic converter gets up to running temperature rapidly.

You could try bypassing the vacuum inhibit valve. IE join the pipes together from either side of it and see if your gear changes are normal. If they are then the valve is being told to stay closed by the ECU for some reason. You'll find it on the firewall. One vacuum line coming from the vacuum distribution block and going in one side and the other heading down towards the gearbox. It's just a small matchbox sized device. It would be unusual for this valve to be faulty but don't rule it out.

Are all your other vacuum operated devices working OK ?

If disconnecting the battery doesn't cure it then a dreaded star diagnosis and reprogram might be the next step.

Let me know what happens....

 

Stupid me !! I didn't read the first part of your post. You did have a flat battery.

Disconnecting is probably gonna cure the problem.

C's are really fussy about battery charging while still connected.

Oh and I doubt that the axle speed sensor has anything to do with the problem. Cleaning the connector to it with a bit of contact cleaner is probably all it needs anyway.

 

I experienced the same problem on my 1999 C230, staying in low gear until the car engine had warmed up. The dealer mentioned they had to replace some module that would have cost me approximately $1,400 if the car wasn't under warranty.

 

Hi, I just recently (in the last couple of days) began to have a similarissue with my C180 (2001). I am wondering if there was a definitive solution to this problem ?.

My symptoms are:
Intermittent fault on start-up where the traction control program comes up as off line.
Intermittent fault where the Auto box does not change up from first (if I stop and restart the engine it's ok again, does not seem to be engine temp related!.).
My battery seems to be running down also - each timeI start theengine the starter turns slower. Thought there is noerror message about alternator or similar failure ??

Any suggestions before I need to resort to the dealerships"keep changing things till it works" assistance ??

 

No absolute definitive answer that I'm aware of. But I'd nearly bet money that all your trouble is battery related. If you're still on the original battery in a 2001 c-class then I'd advise changing it for a new one before you go spending money on anything else. You're gonna need one pretty soon anyway. Also check any non-factory fit accessories like cellular phone handsfree kits and alarms or in-car audio and make sure they are all switching off when they should. Hansfree kits, reversing sensors, cd players, amplifiers etc usually have two supplys. One constant 12 volts, and one which is supposed to be supplied via the accessory position on the ignition switch. Some installers connect both thesecables direct to the constant supply outta pure laziness. This usually doesn't cause a problem in a vehicle with a battery which is in tip-top condition and when the car is in use every day. The problem arises when you have an older more "tired" battery in a car which spends a lot of time parked up. Also check the usual silly stuff like trunk/boot lights aren't staying on all the time. Low battery voltage can definately cause all the problems you've got. It makes sense that your car starts and runs properly second time you start it.This is because the battery has a higher voltage second time around after the brief boost from the alternator whilethe engine was running first time around. Oh yeah.. it's possible that you don't actually have any accessories that aren't turning off. You could well just have a failing battery. I've seen that plenty of times.Hope this helps.